Electric lamp.



Nu. 64!,l96. Patented Jan. 9, I900. C. VAN DEVENTER.

ELECTRIC LAMP. (Kpplicabion filed Jim: 3, 1899.: (m moduli) I 3' WITNESSES: Ii INVENTOR y/ E G W m ATTORNEY "n45 NORRI$ warms co. wom-uwonwmummou, u. c,

CHRISTOPHER VAN DEVENTER, OF NEW YORK, N. Y.

ELECTRIC LAMP.

SPECIFICATION forming part of Letters Patent No. 641,196, dated January 9, 1900.

Application filed Juno 3, 1899. Serial No. 719,259. (No model.)

To aZZ whom it may concern.-

Be it known that I, CHRISTOPHER VAN Dn- VENTER, a citizen of the United States of America, and a resident of New York, in the county and State of New York, have invented a new and useful Improvement in Electric Lamps, of which the following is a specification.

My invention relates to that class of electric lamps in which refractory non-electric conductors cold and electric conductors hot, like kaolin, magnesia, and several other materials, are employed as the principal source of light in the lamp.

The general object of the invention is to produce a lamp of this character adapted to fulfil, by its cheapness of manufacture and convenience in operation,all the requirements of a commercial and practical electric lamp. More particularly the object is to dispense with other forms of energy, like heat from gas, for heating the light-giving substance to the temperature of proper conductivity and to heat the conductor effectually by means of the electric current.

I am enabled to accomplish the results sought by a simple combination consisting in means adapted to impart all its heat, which is produced electrically, to the refractory material, said means being for this purpose an electric heater embedded entirely within the mass of the substance. The form of electric heater which I have adopted thus far consists of a coil of Wire wound around an ordinary clay pipe-stem or its equivalent, which may be any substance adapted to withstand heat. The electric conductor of this heater serves not only as a primary heater for raising the temperature of the lightgiving substance, which I call a finger, but it performs also a secondary but equally important function, for it serves the purpose of one pole or terminal of the finger. Any number of conductors lying at another portion of the finger, preferably upon the outside and in contact therewith, form the other terminal of the finger, and consequently after the finger is heated by the electric heater the current can be switched so as to pass through the heater, through the finger, and through the terminals on the outside of the finger.

Figurel is a general elevation of the lamp,

on a small scale, shown applied in use in one of the usual ways by being suspended from the ceiling by a flexible electric conductor.

Fig. 2 is a diagram of the circuits from a given generator through thelamp and switches and back again to the generator, so that the complete operation of the lamp may be understood. The drawing in Fig. 2 is made on a much larger scale than that in Fig. 1. Fig. 3 is an enlarged elevation of one of the im portant details of construction shown in mere outline in Fig. 2.

a is a finger of magnesia or other substance which has the property of having an enormously high resistance when at the natural temperature and a comparatively low resistance, being of about the right resistance for an electric lamp, when at a comparatively high temperature. I have shown it in the form of a rod, and to easily identify it I call it a finger, but it is evident that shape in this invention has little to do with the principles or claims of the invention. Located entirely within the finger is an electric heater consisting of a coil of wire I) (shown byafull zigzag line) passing around the cylinder 0, of refractory material, and through the whole length of said cylinder, asshown by a line 61 made of dots and dashes. The refractory cylinder 0 and conductors b and d are so 10- cated as to be completely surrounded by the material of the finger a, so that when the electric heater is under operation said finger will be quickly raised to the proper temperature at which it becomes of a sufiEiciently low resistance to conduct a comparatively low voltage current for being made incandescent. It is unnecessary to specify the materials to be used in the electric heater, as this department of art is well known; but the wires 1) and d should be made of such a substance as to withstand the proper temperature without fusion. The cylinder 0 may be hollow or solid, and may consist, for example, of a section of an ordinary clay pipe-stem, or it also may be made of the same substance as the finger a. Again, my invention is broad enough to permit the omission of the cylinder 0 without departing from the spirit thereof, as this element of the invention consists, essentially,of an electric heater located in the interior of the finger a.

On the outside of the finger and on opposite sides thereof there are located several conductors 6, extending, preferably,throughout the whole length of the finger a, and these conductors, only two being shown in the drawings for the sake of illustration, are made of a material which will not fuse by heat, and if the finger is outside of a Vacuum they should be made of incombustible material.

[ f represents a glass globe or bulb, which may be evacuated or not, according to the circumstances; but, as far as the invention is concerned, it is immaterial as to what kind of and how much gas surrounds the finger.

During the first part of the operation of the lamp the electric heater only is in circuit, and when the temperature of the finger is sufficient the current is switched so as to pass from the electric heater through the finger a to the outside and then through the filaments e. In order to carry on this operation, I pro vide a row of insulated contacts g, h, t',j, and 2c. The contacts 9 and t' are the terminals of the filaments e, and they are separated by the insulated contact h, which is merely an idle piece serving as an insulator. j is a similar piece between the contacts 2' and 7a, which latter is one of the terminals of the electric heater-namely, of the conductor (1. The terminal of the other conductor 19 of the electric heater connects permanently with the dynamo Z, while the other pole of the dynamo is connected to the switches m and n, which are respectively normally or at starting the de- Vice located in contact with the terminals 7c and h. The current can therefore go from the pole s of the dynamo through the switch m, through the contact or terminal is, through the conductor 01, through the conductor 6, and thence to the pole q of the same dynamo Z. In a second or two the finger, by means of the current which passes over the above-outlined circuit, raises the temperature of the finger a to the proper increment. The next step consists in turning the switches 'm and 7t to the left, so that two currents can pass as follows: the one from the polep to the switch m, to the contact 2', to the filament e, to the cond uctor b,and thence to the pole g, and the other current passes from the pole p to the switch n, to the terminal g, to the filament e, to the conductor b, and thence to the terminal q. These two currents therefore pass between the electric heater in the interior of the finger a and the filaments e on the exterior thereof, and consequently the finger is no longer heated by conduction of heat, as when heated by the electric heater, but is now heated directly by the current conducted through the finger, and consequently the high efficiency of the finger in generating light by an electric current is made use-of.

I claim as my invention 1. An electric lamp, consisting of the combination of a finger of refractory material, being a non-conductor cold, and a conductor hot, an electric conductor embedded in said mass substantially throughout the length thereof and forming a heating-circuit from one end of the finger to the other and back again, conductors on the exterior of the finger and in contact therewith throughout their length, said electric conductors being located inside and outside so as to be adapted to permit an electric current to fiow from the interior to the exterior of the finger.

2. An electric lamp consisting of the combination of a finger of refractory material, a refractory cylinder within the material, an electric conductor passing through the inte rior of the cylinder and helically around the exterior, filaments upon and in contact with the outside of said finger, and an electric switch adapted in one phase, to conduct a current through said conductor only, and in another phase from said conductor to said filaments through the material of said finger.

In testimony whereof I have hereunto subscribed my name this 3lst day of May, 1899.

CHRISTOPHER VAN DEVENTER. [Ls] Witnesses:

EDWARD P. THOMPSON, WILLIAM J. BARKER. 

